Key takeaways
- Using bottled lemon juice: It often lacks the fresh aroma and can taste more sharply acidic. Freshly squeezed lemon gives a rounder, more fragrant sourness.
- Skipping dilution: Pouring the ingredients directly over ice without shaking produces a hotter, less integrated drink.
- Making the syrup too sweet: A thick honey syrup can dominate the whisky. Start with a 1:1 honey-to-water formula and adjust after tasting.
- Adding too much peat: A 30 ml float is not a small adjustment; it can turn the drink into a smoke-led whisky cocktail. Increase the float in 2.5 to 5 ml steps.
- Using warm syrup: Warm syrup melts ice quickly and reduces control over dilution. Cool it before mixing.
- Failing to strain ginger: Ginger fibers can produce an unpleasant texture and continue extracting flavor in storage.
The most balanced penicillin cocktail recipe uses 60 ml blended Scotch, 22.5 ml fresh lemon juice, 22.5 ml honey-ginger syrup, and a 7.5 ml float of smoky Islay Scotch. This ratio keeps the drink tart and warming rather than syrupy, while the peated whisky stays on the nose instead of overpowering the citrus and ginger.
The Penicillin is a modern Scotch whisky sour created by Sam Ross in New York in the early 2000s. Its structure is simple: a mellow blended Scotch forms the base, lemon supplies acidity, honey-ginger syrup adds sweetness and heat, and a small measure of smoky whisky creates the signature finish.
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Classic Penicillin Cocktail Recipe
| Ingredient | Amount | Purpose |
|---|---|---|
| Blended Scotch whisky | 60 ml (2 oz) | Soft, malty base |
| Fresh lemon juice | 22.5 ml (¾ oz) | Tartness and structure |
| Honey-ginger syrup | 22.5 ml (¾ oz) | Sweetness and spice |
| Peated Scotch whisky | 7.5 ml (¼ oz) | Smoky float |
| Ice | As needed | Chilling and dilution |
Method: Add the blended Scotch, lemon juice, and honey-ginger syrup to a shaker with ice. Shake firmly for about 10 to 12 seconds, then strain over one large ice cube or fresh rocks ice in a low glass. Slowly pour the peated Scotch over the back of a spoon so it rests near the surface. Garnish with a thin slice of candied ginger or a piece of fresh ginger.
How to Make Honey-Ginger Syrup
A reliable starting formula is equal parts honey and water by volume, with fresh ginger added to taste. For one small batch, combine 120 ml honey, 120 ml water, and 20 to 30 g thinly sliced fresh ginger. Warm the water and ginger gently, remove the pan from the heat, stir in the honey, and steep for 15 to 20 minutes. Strain, cool, and refrigerate in a clean sealed container.
- Warm the water and ginger without boiling. Excessive heat can flatten the ginger’s fresh aroma and make the syrup taste cooked.
- Stir in the honey after removing the pan from the heat. This preserves a brighter honey flavor.
- Steep for 15 to 20 minutes. Shorter steeping gives gentle warmth; longer steeping produces a sharper, more medicinal ginger note.
- Strain and chill completely. Cold syrup mixes more predictably and helps the finished drink chill quickly.
The syrup should pour easily but still taste distinctly honeyed. If it is too thick, add a small amount of water. If it tastes weak in the finished drink, increase the ginger in the next batch rather than adding extra syrup to the cocktail, because additional syrup also increases sweetness.
Choosing the Right Ratio
The classic equal amounts of lemon juice and honey-ginger syrup are a useful starting point, but the ideal balance depends on the whisky, the acidity of the lemon, and personal preference. Use the following adjustments one at a time so you can identify what changed.
| Preferred style | Blended Scotch | Lemon | Honey-ginger syrup | Smoky float |
|---|---|---|---|---|
| Classic balance | 60 ml | 22.5 ml | 22.5 ml | 7.5 ml |
| Drier and sharper | 60 ml | 25 ml | 15 ml | 7.5 ml |
| Softer and sweeter | 60 ml | 20 ml | 25 ml | 5 ml |
| More smoky | 60 ml | 22.5 ml | 22.5 ml | 10 to 15 ml |
| Lower-alcohol profile | 45 ml | 22.5 ml | 22.5 ml | 5 ml |
These quantities produce one drink. A 60 ml base plus 22.5 ml each of lemon and syrup gives a strong but rounded sour. Reducing the base to 45 ml lowers the whisky intensity, but the drink may taste more citrus-forward unless the syrup and lemon are reduced slightly as well.
Whisky Substitutions and Smoke Levels
For a gentle smoky finish
Choose a lightly peated Scotch for the float and keep it at 5 to 7.5 ml. This is the best choice for someone who enjoys the aroma of smoke but does not want medicinal or heavily charred flavors. Pouring the smoky whisky last preserves a fragrant top layer that gradually integrates as the drink is consumed.
For a pronounced smoky Penicillin
Use 10 to 15 ml of a strongly peated Scotch, but keep the base whisky smooth and relatively restrained. Increasing both the base and the float can make the cocktail hot, aggressive, and less balanced. A strong float is best served over a large cube, which melts more slowly and limits rapid dilution.
For a softer, less smoky version
Use a blended Scotch with no additional float, or add only 2.5 to 5 ml of lightly peated whisky. The result loses some of the classic campfire character but retains the lemon, honey, and ginger structure. This version is suitable when serving guests who are unfamiliar with Scotch.
For a more malt-forward version
A mellow single malt can replace the blended Scotch, but it may bring more oak, fruit, or spice. Keep the float small at first—about 5 ml—because a distinctive single malt combined with a heavily peated float can obscure the ginger and lemon. The cocktail’s base should support the other ingredients rather than compete with them.
Step-by-Step Mixing Method
- Chill the serving glass. Fill a rocks glass with ice while preparing the drink, or refrigerate it for several minutes. A cold glass slows dilution after straining.
- Measure the whisky, lemon, and syrup. Use a jigger rather than free-pouring. The 60:22.5:22.5 ratio is forgiving, but an extra 10 ml of syrup can make the cocktail noticeably sweet.
- Add the ingredients to a shaker with ice. Fresh, hard ice chills efficiently and provides the small amount of dilution needed for a sour.
- Shake for 10 to 12 seconds. The goal is a cold, integrated drink with a modest amount of water added from the melting ice. Under-shaking leaves the texture warm and concentrated.
- Strain onto fresh ice. Fresh ice avoids carrying cloudy, rapidly melting shaker ice into the serving glass.
- Add the smoky float slowly. A spoon-backed pour gives the drink a more noticeable aromatic layer. Pouring directly into the center blends the smoke more quickly.
- Garnish lightly. Candied ginger reinforces the syrup, while a thin fresh-ginger slice gives a sharper aroma. Avoid an oversized garnish that overwhelms the drink.
Worked Example: Adjusting a Batch for Four
For four classic Penicillins, multiply every liquid ingredient by four: 240 ml blended Scotch, 90 ml lemon juice, 90 ml honey-ginger syrup, and 30 ml peated Scotch. Combine the blended Scotch, lemon, and syrup in a chilled pitcher, then shake or stir each serving with ice rather than chilling the entire batch without dilution.
If you want to batch the drink in advance, add approximately 60 ml of cold water to the four-serving mixture to approximate some shaking dilution. This is an estimate, not a fixed rule: large ice, vigorous shaking, and serving temperature all change how much water enters the drink. Add the smoky whisky to each glass individually so guests can receive different smoke levels.
Common Mistakes That Change the Drink
- Using bottled lemon juice: It often lacks the fresh aroma and can taste more sharply acidic. Freshly squeezed lemon gives a rounder, more fragrant sourness.
- Skipping dilution: Pouring the ingredients directly over ice without shaking produces a hotter, less integrated drink.
- Making the syrup too sweet: A thick honey syrup can dominate the whisky. Start with a 1:1 honey-to-water formula and adjust after tasting.
- Adding too much peat: A 30 ml float is not a small adjustment; it can turn the drink into a smoke-led whisky cocktail. Increase the float in 2.5 to 5 ml steps.
- Using warm syrup: Warm syrup melts ice quickly and reduces control over dilution. Cool it before mixing.
- Failing to strain ginger: Ginger fibers can produce an unpleasant texture and continue extracting flavor in storage.
Storage and Ingredient Ownership
Fresh lemon juice is best used the same day, when its aroma and acidity are most vivid. Honey-ginger syrup should be refrigerated in a clean sealed container and used promptly; discard it if it develops mold, fermentation, an unusual smell, or visible pressure. Because homemade syrup contains water and fresh ginger, it is perishable even though honey itself stores well.
Whisky is less fragile but should be stored upright, away from heat and direct sunlight. The cork or cap is usually the first closure component to cause problems, especially if the bottle is stored on its side and the spirit remains in contact with the closure. Clean the jigger and shaker immediately after use so honey residue does not harden around seams, strainers, or threaded lids.
Frequently Asked Questions
What is the correct penicillin cocktail recipe ratio?
The classic ratio is 60 ml blended Scotch, 22.5 ml fresh lemon juice, 22.5 ml honey-ginger syrup, and a 7.5 ml float of peated Scotch. This produces a balanced drink with equal tart and sweet components and a noticeable but controlled smoky finish.
Can I make a Penicillin without a smoky whisky float?
Yes. The float is a defining modern feature, but the cocktail still works without it. Use a lightly peated whisky, add only 2.5 to 5 ml, or omit it for a softer Scotch, lemon, honey, and ginger sour.
How can I make the Penicillin less sweet?
Reduce the honey-ginger syrup to 15 ml and keep the lemon at 22.5 to 25 ml. Do not simply add more lemon after making the drink very tart; reducing the syrup first preserves a more stable whisky-to-acid balance.
What can replace honey-ginger syrup?
Use a ginger syrup plus a small amount of honey, or combine simple syrup with freshly grated ginger and let it infuse briefly. Agave syrup can replace honey for sweetness, but it changes the flavor and gives the drink a cleaner, less rounded finish.
Should a Penicillin be served up or over ice?
It is commonly served over fresh ice in a rocks glass. One large cube melts more slowly and keeps the smoky float distinct, while several smaller cubes chill quickly but dilute the drink faster.
How long does homemade honey-ginger syrup last?
Refrigerate it in a clean sealed container and use it promptly, ideally within about one to two weeks. There is no reliable universal shelf life for homemade syrup because hygiene, water content, and storage temperature vary; discard it at the first sign of spoilage.
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